Process for finishing lightweight fabrics



Patented May 9, 1939 rnoon'ss ron FINISHING LIGHTWEIGHT FABRICS Florence M. Ford, Wilmington, Del., assignor to lmmgton, Del,

.loseph Bancroft & Sons 00., Wi a corporation of Delaware No Drawingu Application November 29, 1935, Serial No. 52,073

3 Claims. (oi. a-iie) I This invention relates to a process for finishing lightweight fabrics, such as organdies, voiles, marquisettes and the like.

' The primary object of the invention is to give 5 a sheer, transparent and stiff effect to the fabric which is much desired in such lightweight fabrics.

in carrying out the invention, the fabric is blemhed in the usual manner. It is then subjected to a cellulose dissolving solution, preferably ill a solution madefrom copper sulphate ammonia and caustic soda to be later described. The so-.

lution contains a wetting agent, preferably that known as Avirol #80, about 2 lbs. of the wetting agent to 50 gallons of the solution. The teml perature of the solution should be kept as low as possible, preferably at about 5 to 15 0., or below. 'i e time of immersion in the solution may be practically instantaneous or up to about 2% seconds. One way of applying the solution is to an draw the fabric through nip rolls known as a padder or mangle, with the lower roll running suficiently deeply in the solution td bring enough up to impregnate the fabric. The low temperature of the solution, together '25 with the presence of the wetting agent, increases the activity of the solution on the fabric.

The nip roll-s squeeze ofi any excess solution which is of importance inasmuch as the solution tends to dissolve or substantially dissolve the pro- 30 jecting fibers or fuzz. Any such dissolved cellulose, if allowed to remain on the surface of the cloth, might produce streaks and other objectionable characteristics. The nip rolls remove the same in removing any excess solution.

35 The fabric is now run througha. sulphuric acid bath of approximately 7% strength to set any regenerated cellulose in the body of the fibers which is formed by the action of the dissolving solution, The fabric is now washed in water, thoroughly to 40 remove all traces of acid, so that it becomes neutral. While in the wet state it is then mercerized, after squeezing, to obtain as nearly a uniforn moisture content as possible. For a meroerizing solution I employ 100 Tw. caustic soda 45 or 46% NaOH, leaving the fabric in the solution for about 45 seconds, whereupon the fabric is washed in preferably cold water to remove as much of the caustic soda as possible, and down to the point where the concentration of the caus- 55 washedand dried on the swing tender at as great a width as possible without resulting in damage.

The modified cellulose produced by the action of the dissolving solution, is soluble in caustic soda when it passes through the-range of 10 nor- 5 mal (400 grams per liter) to 2 normal (80 grams per liter). The 150 Tw. caustic, is above 10 normal strength, and by washing continuously iii cold water I reduce, as above described, the strength to 10 normal, and by further washing-10 bring it through the range of about 10 normal to about 2 normal, after which it is neutralized by the weak solution of acid above referred to and then washed and dried as described. The above treatment gives a sheer, transparent and stiff effeet to the fabric which makes it particularly useful in. connection with lightweight fabrics of the character mentioned, although it is to be understood that the invention is applicable for the treatment of other .types of fabric.

.This dissolving solutionis of the following composition: copper 19.3 grams per liter, ammonia 124 grams per liter, sodium hydroxide 24 grams per liter. A wetting agent is preferably added, such as Avirol, 2 lbs. to 400 lbs. of the so- 25 lution. This is preferably added at the last step in the making of the dissolving solution. The dissolving solution may be prepared as follows: Dissolve 60 lbs. of copper sulphate in 116.50 liters of water, and add 52% liters of 26 B. 30 aqua ammonia and agitate until the basic copper just formed is redissolved. Cool or allow to cool to about 15 C. Any iron present will quickly settle. Of this, pour 95.13 liters into 'a mixer and add 66.5 liters of 26 B: ammonia.

Dissolve 10.4 lbs. of caustic soda (76% NazO) in suflicient water to make 15.2 liters and cool to about '15" Q; and add 29 lbs. of cracked ice.

Pour the second mixture slowly into the first, agitating until thoroughly mixed, which lowers 40 the temperature to about 15 C.

While the above dissolving solution gives the best effect I may use other cellulose dissolvin solutions, particularly such as will form a homogeneous phase with the wetting agent and I here mention dissolving solutions such as a sulphuric 1 acid solution of about to 51 B., a phosphoric acid, zinc chloride or other known acids which react with cellulose in the fibers of the fabric and which will form a homogeneous phase with the 50 wetting agent. In the case of any such solutions, however, there is no need for the setting bath as in the case of the copper sulphate ammonia and caustic soda solution. It is sufficient to wash and then mercerize the fabric in the wet state as 55 hereinbefore described. These solutions can be used at room temperature.

I claim:

1. The process of finishing cotton fabric which comprises subjecting the fabric to a cellulose dissolving solution of copper sulphate ammonia and caustic soda in molecular proportions of the copper "sulphate and caustic soda, i. e., one mol of copper sulphate to two of caustic soda, the temperature of the solution being about 5 C. to 152 C. or below, removing excess solution to remove dissolved cellulose, setting regenerated cellulose with an acid solution, washing with water, and, while wet, mercerizing the fabric by subjecting it to a caustic soda solution of strength greater than 10 normal, washing to reduce the strength to about 2 normal, neutralizing with acid, washing with water and drying.

2. The process of finishing cotton fabric which comprises subjecting the fabric to a cellulose dissolving solution of copper sulphate ammonia and caustic soda in molecular proportions of the copper sulphate and caustic soda, 1. e., one mol of copper sulphate to two of caustic soda,'the temperature of the solution being about 5 C. to 15 0.

or below, removing excess solution to remove dissolved cellulose, setting regenerated cellulose with ,an acid solution, washing with water, and while wet, mercerizing the fabric by subjecting it to a caustic soda solution of strength greater than 10 normal, washing to reduce the strength to about 2 normal, neutralizing with 'acid, washing with .water and drying on a tenter of maximum permissible width.

3; The process of finishing cotton fabric which comprises subjecting the fabric to a cellulose dissolving solution of copper sulphate ammonia and caustic soda in molecular proportions of the copdown to about 2 normal, neutralizing with acid and drying.

FLORENCE M. roan. 25 

